Carbon and molecular diversity of life

Question 1

Why is carbon the backbone of life?

Answer 1

70-95% water, but the rest consists mostly of carbon-based compounds

• carbon enters the biosphere through the action of plants
• has ability to form large, complex and diverse molecules (proteins, DNA, carbohydrates and others are all composed of carbon compounds)

Question 2

Who is Stanley Miller?

Answer 2

provided evidence that organic compounds might have been the first step in the origin of life, in 1953

Question 3

What is the Miller’s Experiment?

Answer 3

closed system to simulate the conditions of early earth

1. water mixture in flask was heated -> vapor entered the atmosphere
2. the atmosphere contained a mixture of Hydrogen gas, methane, ammonia and water vapor
3. sparks were discharged to mimic lightning
4. a condenser cooled the atmosphere, raining water and any dissolved molecules down the flask
5. as materail cycled through the apparatus, miller periodically collected samples for analysis

Question 4

What were the results of miller’s experiment?

Answer 4

• variety of organic compounds that play key roles in living cells were synthesised in miller’s apparatus
• simple compounds like formaldehyde CH2O, hydrogen cyanide HCN
• complex molecules like amino acids and hydrocarbons

Question 5

What was the conclusion to miller’s experiment?

Answer 5

organic compounds may have been synthesised abiotically on the early Earth, setting the stage for the origin on life

Miller’s experiment helped bring the abiotic synthesis of organic compounds into the context of evolution

Question 6

Whats the principle of the formation of bonds with carbon?

Answer 6

electron configuration is the key to an atom’s characteristics -> determines the kinds and number of bonds an atom will form with others

• Carbon can bond covalently to four other atoms -> has 4 valence electrons
• its bonding versatility allows it to form many diverse molecules, incl carbon skeletons

Question 7

What enables carbon to form complex molecules?

Answer 7

its electron configuration -> gives covalent compatibility with many different elements

Question 8

What are the most frequent partners of carbon?

Answer 8

• hydrogen
• oxygen
• nitrogen

Question 9

What are carbon chains?

Answer 9

the linking of covalent bonds of two or more carbon atoms to form a chain

• form the skeletons of most organic molecules
• vary in length and shape (straight, branched, rings)
• vary in number and location of double bonds

Question 10

What are hydrocarbons?

Answer 10

=organic molecules consisting only of carbon and hydrogen

• found in many of a cell’s organic molecules, but are not prevalent
• can undergo reactions that release a large amount of energy (petroleum, fats)

Question 11

What is petroleum made of?

Answer 11

partially made of decomposed remains of organisms that lived millions years ago

Question 12

Why are petroleum and fats hydrophobic?

Answer 12

a great majority of their bonds are non-polar carbon-hydrogen linkages

Question 13

What are isomers?

Answer 13

molecules with the same molecular formula, but differ in structure amd properties

• the greater the size of carbon skeleton, the greater the possibility of isomers

Question 14

What are structural isomers?

Answer 14

different covalent arrangement of atoms, number of double bonds

Question 15

What are geometric isomers?

Answer 15

carbons have covalent bonds at the same atoms, but these atoms differ in their spatial arrangement due to the inflexibility of double bonds

• cis and trans isomers

Question 16

What are Enantiomers?

Answer 16

mirror images of each other, that differ in shape due to the presence of an asymmetric carbon (attached to 4 different molecules)
- important in pharmaceuticals
- two enantiomers of a drug may have different effects -> shows that organisms are sensitive to even subtle variations in molecules

Question 17

What are chemical groups?

Answer 17

give organic molecules distinctive chemical properties
- may participate in chemical reactions or contribute to function indirectly by their effects on the shape of the molecule

• eg estradiol and testosterone: have the same skeleton but different chemical groups -> different functions

Question 18

What are functional groups?

Answer 18

chemically reactive groups of atoms within an organic molecule that are involved in chemical reactions

Question 19

What are the most important 7 functional groups?

Answer 19

• hydroxyl -OH
• carbonyl >CO
• carboxyl -COOH
• amino -NH2
• sulfhydryl -SH
• phosphate -OPO3 2- or P
• methyl -CH3

all of them are hydrophillic, except for methyl (chemically unreactive)

Question 20

What is one of the purposes of the hydrophillic functional groups?

Answer 20

increase the solubility of the organic compound in water

Question 21

What is one of the functions of methyl functional group?

Answer 21

• chemically unreactive

often acts as a recognizable tag on biological molecules

Question 22

What is ATP?

Answer 22

= adenosie triphosphate

• organic molecule adenosine is attached to a string of 3 phosphate groups

Question 23

What is released when ATP reacts with water?

Answer 23

inorganic phosphate HOPO3 2- and energy